1. Field of the Invention
The present invention relates to a piezoelectric actuator unit, and a liquid transporting apparatus using the piezoelectric actuator unit.
2. Description of the Related Art
A piezoelectric actuator which drives an object by using a piezoelectric deformation (also called as a piezoelectric distortion) of a piezoelectric layer has hitherto been used in various technical fields. A common piezoelectric actuator includes a piezoelectric layer and two types of electrodes provided to the piezoelectric layer, and causes a piezoelectric deformation in a portion of the piezoelectric layer sandwiched between these two types of electrodes (hereinafter, called as an ‘active portion’) by applying a voltage between the two types of electrodes.
Incidentally, in the abovementioned piezoelectric actuator, sometimes there is a short-circuit between the two types of electrodes or a dielectric breakdown of the active portion due to a crack in the active portion or a phenomenon such as a migration of an electrode material. At this time, an overcurrent (an excess electric current) passes between the two types of electrodes, and there is a trouble such as a breakdown of a circuit component.
An apparatus which detects a breakdown due to short-circuit of a piezoelectric element (active portion) of a piezoelectric actuator for an ink jet recording apparatus has been disclosed in Japanese Patent Application Laid-open No. 2008-44304. This apparatus detects the short-circuit by detecting a leakage current when a DC voltage is applied to the active portion.